1: A single 10000 RPM drive would be limited by only being able to send 150MB on the cable. 2 7200 RPM drives would be able to theroatacly move 150MB (SATA) each meaning 300. The 10000 RPM drive would still find stuff 2ms quicker

3: Watercooling is very unnessary on AMD's since they run pretty cool now and become unstable before they reach their thermal limit on a good heatsink and fan